In Chapter 2, I responded to widespread contemporary criticisms of any notion of moral objectivity; Chapter 3 highlighted the promise of new arguments in philosophy of science in capturing the integrity of ethics. But many influential relativist criticisms of moral realism focus on the issue of progress. In addition, those naturalists who wish to downgrade ethics compared with the exact sciences share some of these objections. This chapter counters versions of these conventionalist objections tailored to my historical argument and then explores an alternative, overall view that resembles realism: Putnam's neo-Kantian “mind dependent objectivity.” By examining nuanced ontological, epistemological, and semantic differences, I hope to show that moral realism is more plausible than Putnam's neo-Kantianism. Nonetheless, this book's basic depiction of ethical objectivity and progress and its separation of clear issues, affecting the capacity for moral personality and democracy, from difficult cases of deliberation can cohere with the best general view.

I will outline nine further objections to the idea of moral progress and answer them one by one. The first – a conventionalist mimicking of realism – reinterprets the historical argument for ethical advance philosophically. It suggests that what I call moral discoveries are simply new conventions; the ethical discovery-based empirical disagreements that drive complex political and moral clashes are convention-based empirical disputes.